10-08-2021, 04:11 PM | #1 |
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Engine fault code P0420
I have a 2017 M240xi with 45,000 miles. The check engine light went on today with a error code of P0420. Which is the 'Catalyst System Low Efficiency'. More specifically, a problem with the catalytic converter or the oxygen sensors.
I find it hard to believe that the CAT's are bad on this car, especially when my Infiniti G35 had 210,000 miles with the original CAT's and oxygen sensors. I have since cleared the error. Will see if it comes up again. I will be adding some fuel injector/fuel system cleaner to see if it helps. Any suggestions appreciated. |
10-23-2021, 09:31 AM | #2 |
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Get the OBDFusion app for your phone or tablet. If your device is iOS then get a wifi adapter to plug into the obd2 port. If it's android you need to buy a Bluetooth adapter. You need to look at the o2 sensors' responses to changes in engine speed and load. The sensor may be lazy or bad. Also, the emissions system has a longer warranty than the rest of the car or the drivetrain.
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10-27-2021, 10:20 PM | #3 |
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The P0420 code came up again after I cleared it. After reading the warranty book it states that my state which I live, is one of many that have a 7 year/70K mile emissions warranty and the catalytic converter is covered. I brought it to the dealer and they said that its out of warranty and it will cost $199 to examine the code and diagnose it. They came back 2 hours later and said it was the catalytic converter and it be covered under the emissions warranty. They cost of the CAT is approximately $2,000 if it wasn't. Made an appointment for next week.
Thanks for the help! |
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12-05-2023, 11:14 AM | #4 |
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Drives: 2014 BMW 228i, 2017 BMW M240i
Join Date: Apr 2021
Location: Northern Virginia
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Downstream sensor is likely bad. Replacement is incredibly easy.
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